HUNDREDS of workers at Greencore's Hull factory are planning a 24-hour walkout over changes to their pay and conditions.
Employees at Greencore Cakes and Desserts will take industrial action on Wednesday.
Unite, the UK's biggest union, said the company is forcing its workers to take the action because of the changes it is attempting to introduce.
The mass protest, from 5am on Wednesday to 4.59am the following day, will be the first to affect the Hull site and will hit its production of cakes supplied to supermarkets including Asda, Tesco and Sainsbury's.
About 500 workers have been fighting to claw back pay after Greencore suspended their terms and conditions in October 2011.
Unite say employees are losing up to £40 per week from their wages.
Michael Hancock, regional officer at Unite, said: "This workforce has never taken a day's strike action but feel they have no other option.
"We urge the company now to take heed. They have brought this workforce to the point of despair.
"They have forced the workers to take their employer to court over what is rightfully theirs.
"They are determined to stand up for decent treatment and Unite will support them every step of the way."
According to Unite, Greencore, whose revenue rocketed by nearly 45 per cent in 2012, is seeking to impose changes to terms and conditions and remove shift, overtime and bank holiday pay.
The workers recently voted to take action, angered by the company's breach of promise.
Last year, Greencore was forced by a tribunal to reverse the changes, which the union claims would strip the workforce of £1.2m in wages.
However, Unite said the firm has attempted to dodge the court's ruling by simply issuing new contracts to the workforce.
Jennie Formby, national officer for the food industry at Unite, has accused the firm of "robbing wage packets".
She said: "When brought into line by the law, Greencore simply ignores it.
"It is entirely shameful behaviour."
Unite is now appealing to retailers such as Asda to seek other suppliers.
Despite repeated requests, Greencore did not respond to the Mail's request for a comment.
